Polydopamine-derived nitrogen-doped graphitic carbon for a bifunctional oxygen electrode in a non-aqueous Li-O₂ battery

Nitrogen-doped graphitic carbon was developed through a simple, facile and controllable method in the pursuit of advanced oxygen electrode materials for use in non-aqueous Li-O₂ batteries. These materials were synthesized by directly coating a thin layer of polydopamine (PDA) on the cage-like structure of graphitic carbon followed by subsequent carbonization without the aid of metal catalysts. By virtue of the versatile coating ability associated with the high nitrogen content, dopamine was demonstrated to be an effective precursor for the preparation of nitrogen-doped graphitic carbon. Various experimental results indicated that dopaminederived nitrogen-doped graphitic carbon improved the performance of Li-O₂ batteries in terms of capacity, rate capability and cycle life. The enhanced performance was attributed to the formation of active nitrogen functional groups, which benefit the fast electrochemical kinetics of the oxygen reduction and oxygen evolution reactions in the oxygen electrode of Li-O₂ batteries.